How to calculate a discount
- Enter the percent off and the original price in the first card.
- The sale price appears in large type, with the amount you save underneath.
Formula and examples
Sale price = original price × (1 − discount ÷ 100), and savings = original × discount ÷ 100. A 25% discount on 80 saves 20 and leaves 60. A 40% discount on 59.99 saves 24.00 and leaves 35.99.
Stacked discounts do not add up. "20% off, then an extra 10% at checkout" is not 30% off: the second discount applies to the reduced price, so the total is 1 − 0.8 × 0.9 = 28%. Enter the first discount, then use the result as the price for the second.
Sales tax or VAT is usually added after the discount in the US, and already included in the shelf price in the UK and EU. To find the original price from a sale price, use the "is X% of what?" card: if 60 is what you pay after 25% off, you are paying 75% of the original, so enter 60 is 75% of what, which gives 80. Handy for checking whether a "was" price is genuine. All calculations happen on your phone or computer, so it works in the shop with no signal once loaded.
FAQ
How do I calculate 30% off?
Multiply the price by 0.7. For example, 30% off 120 is 120 × 0.7 = 84, saving 36.
Is 20% off plus 10% off the same as 30% off?
No. It is 28% off, because the 10% applies to the already discounted price.
How do I find the original price before a discount?
Divide the sale price by (1 − discount ÷ 100). 63 after 30% off was 63 ÷ 0.7 = 90.